Productivity of Florida springs

PRODUCTIVITY OF FLORIDA SPRINGS

NR 163-106

(NONR 580-02)

Third Annual Report

to Biology Branch

Office of Naval Research

Progress from January 1 to December 31, 1955

by J L. Youn and H. T. Odum

with a section by

Delle Natelson Swindale

Department of Biology

University of Florida

Gainesville, Florida

Reproduction in whole or in part is permitted for

i

SJ5 TABLE OF COTENTTS

Introduction
Abstract
Plans for the Future
Reports and publications

Factors that Influence Species Density in Silver Springs, Florida
by J. L. Yount

Studies on Productivity in Silver Springs with comparison with 10
other springs, by II. T. Odum

Macrophytic Communities in Florida Inland waterss
by D. N. Swindale

Studies on Fish Populations
by D. K. Caldwell, H. T. Odum, T. Ilellier, and F. Berry

Prepared by: James L, .oun t and-I toward To Oduum, with a section written by
Delle Natelson Swindal. e

NR: 163-106

Contract: N:ON .. '(.02)

Annual Rate:. .'' (

Contractor: Department >y.. ,., University of Florida, Gainesville
withh Biology Branc.. Of'Lee of r.-'aE Research)

Principal Invst1 L.to: ; S o t

Associates: Howard To Odu : .."'.rity)
Delle Natelcon .-::-le (University of lWisconsin)
David Ko Ca&"ljdi'.I. J mary June 1, 1955

Assistants: Jaes ., Mess;rly (JJm 1 B .'. '. 31 195.
"',;i-,- }Hellier (June 1 .,-. 311 --;

TITLE OF PROn:Jn: t .:.'ITY OF FL.'; 11 SPRING

Objectives: A ft: .'; of basic ;':..:..s* that control productivity uand of -,the

effects of !'-' Su'.ivity on community structure and density by

an analysis of the unique conditions supplied by selected con-

stant temperature springs,

Abstract

a. During current report period

The effect of productivity on species variety has been studied by counts

of diatom species on glass slides at favorable and unfavorable stations within

Silver Springs. Species variety has been presented in a measure that is in-

dependent of sample size, "species per cycle". This measure is based on the

linear increase of accumulated species with logarithmic increase of indivi-

duals counted,, which has beon found approximately true for many kinds of

populations in many communities. Diatom productivity was measured by the

rate of chlorophyll accumulation. The poor station accumulated diatoms and

chlorophyll slowly and was characterized by a large species variety, There

was little change after 79 days. The rich station accumulated diatoms and

chlorophyll rapidly and was characterized by a small species variety that

decreased for 93 days as the density of the population increased. These

results indicated that species variety was decreased by conditions of high

productivity possibly through the action of high densities and competition.

Twelve new diurnal production curves were obtained including two more

on Silver Springs and one each for 10 different Florida Springs. A shallow

oligohaline Spring possessed the highest productivity of 58.0 gm/m2/day; a

shaded and anerobic spring possessed the lowest productivity of 0.66 gm/m2/day.

Findings in further studies in Silver Springs indicated a two fold diurnal

chlorophyll fluctuation in the pseudoplankton going downstream, photosynthetic

quotients corresponding to carbohydrate production on winter or heavily clouded

days, and higher quotients corresponding to protein production on sunny, summer

days; evidences that bell jar estimates of respiration in flowing water com-

munities lead to underestimates; recalculation of mean depth of plant beds

leads to a 5% estimate of photosynthetic efficiency for Silver Springs

(rather than 8%). Correlated with a 20% decrease in the discharge associated

with widespread drought in 19$5-55 the oxygen of the main boil dropped from

about 2.5 ppm to 1.7 ppir. A production measurement by the diurnal oxygen

and carbon-dioxide curve method was made in a somewhat isolated "boat basin"o

Efficiency of production in this stationary, plankton containing water of

Silver Springs origin was about 1%. Further evidence was obtained of nitrate
increase in waters flowing from anaerobic springs over blue-green algae

The area based chlorophyll of the benthic Silver Springs Community was simi-

lar to that in forests and lakes of Europe.

bo Since Start of Project

This contract was begun June 1, 1952, In the two years and a half pre-

ceding the present report period, work of a varied nature outlined the trophic

structure and metabolism of Silver Springso Comparisons made with other

Florida Springs and the intensive study of Silver Springs has been largely

completed. Quantitative comparisons of productivity with other springs are

presented in the present report as well as the effect of productivity on

species density of Silver Springs. Most of the techniques and approaches

outlined in the original proposal have now been applied. The study of fac-

tors affecting qualitative community structure is still being carried out

and will continue until the termination of the project.

PLANS FOR FUTURE

Until termination of the Project:

1. By J. L. Yount

Continue the study of factors that influence species variety in Silver

Springs, in habitats intermediate in productivity with those reported on in

the present progress report, It is planned to continue the study in Silver

Springs for one year (June, 1955 June, 1956) at these stations, in order

to get a more complete picture of successional changes on the introduced

microscope slides.

It is planned also to compare the different springs by using the dia-

tom flora captured by millipore filters. This should reveal differences

between the springs as regards species density, and perhaps in productivity.

2. By HI T, Odum (Duke University)

To complete the mauscript on comparisons of productivity between

springs and to explore the possibilities of applying servo-mechanism ex-

pressions to the Silver Springs community.

REPORTS AND PUBLICATIONS

Published since the last report:

Odum, H. T, and D. K. Caldwell
1955 Fish respiration in the natural oxygen gradient of an anaerobic
spring in Florida. Copeia: lO-106.

Odum, H. To and J. Johnson
1955 Silver Springs and the balanced aquarium controversy. Science
Counselor, December: 128-130.

Odum, H. T. and R. Co Pinkerton
1955 Times speed regulator, the optimum efficiency for maximum
power output in physical and biological systems. American
Scientist. 43: 331-343.

In press:

Odum, H. To
1956 Primary production in flowing waters. Linnology and Oceano-
graphy 2, (42 pp. manuscript, 2 tables, 8 figures).

Sloan, W. C.
1956 A comparative ecological study of the insects of two Florida
Springs. Ecology.

Whitford, L. A.
1956 The communities of algae in the springs and spring streams
of Florida, Ecology.

Completed manuscripts submitted for publication
Caldwell, Do K., Ho T. Odum, T, Hellier, F, Berry
Some characteristics of centrarchid fish populations in a
constant temperature spring (28 pp. manuscript, 4 figures).

Odum, Ho T,
S Productivity of Silver Springs Florida. (120 pp. manuscript,
37 figures, 15 tables).
Odum,H. T,
Efficiencies, size of organisms, and community structure
(16 ppo manuscript, 4 figures),

Manuscripts in Preparation

Odum, H, T. Primary production measurements in 10 Florida Springs.

Yount, J. L. Factors that influence species variety in Silver Springs,
Floridao

FACTORS TIAT CONTROL SPECIES NUMBERS IN SILVER SPRIGS

James L. Youni

Introduction

In the second annual Springs Project report, the hypothesis was presented

that under similar conditions the species varjty is an inverse function

of the community productivity. While investigating this hypothesis, it was

found convenient to investigs.tr generally the factors that control the num-

ber of species in Silver Springs, at least to the extent of classifying them.

There is only sporadic mention in the literature of factors that control

the number of species of an area, Among these one of the most commonly men-

tioned is isolation. For example, the species number~of oceanic islands

have been considerably increased with the appearance of man, simply because

many species were unable to reach them without man's help. Isolation is

regarded by Brooks (1950) as an important factor influencing species density

in ancient lakes.

Other factors mentioned in the literature may be classed under one head-

ing (Hesse, 1943:789) as proximity to the general optimum. For example, tem-

perature is an important factor which affects the number of species of blue-

green algae in a particular area as shown by Copeland in the Yellowstone area,

reported by Vou$ (1950). Other factors that might be listed under this head-

ing are numerous, including such things as hardness of water (Smith, 1950:21),

extent of pollution (Patrick, et al, 1954), food (Hesse, 1943:790), etc. Some

biotic factors that might be listed are competition, grazing, predation, coopera-

tion and the like

In addition to these factors related to proximity to the general optimum,
two others should be mentioned which were examined in some detail here. These
are time or age of the medium, a successional phenomenon and productivity, a

biogenic phenomenon. As shown below, these are apparently of great importance

in the species density of Silver Springs, and presumably of all areas.

l Methods
SIt was thought best to use for this study a group of organisms which

i were common, could be fairly easily counted and identified, and on which

productivity could be estimated. Diatoms were found to best fill these re-
quirements, especially since they attach to microscope slides and since they
remain permanently identifiable after removal from the water.
For the diatom study, then, slide boxes were used by removing the cover

and back; 8 slides were placed in each box and the whole was covered with

1/4" mesh hardware cloth. A group of these boxes were placed at a number
of stations in Silver Springs, by suspending them at approximately one foot

below the surface from stakes placed in the bottom. At various int als,

two slides were removed from each station and later examined at the labora-

tory in Gainesville,
In the laboratory, chlorophyll was removed and estimated quantitatively

by placing the slide in acetone and measuatng the resulting solution with a

spectrophotometer (the method of Richards and Thompson, 1952), The slide

was allowed to dry and placed on the microscope; immersion oil was added

directly to its surface and the diatoms were identified and counted. The

principal monographs used for identification were those of Boyer (1916),
Hustedt (1930) and Tiffany and Britton (1952).

After a period of study, during which the various species were learned

and errors in technique were overcome, new sets of slides were placed at

the various stations and two slides were removed at different intervals,

Ten microscopic fields were counted on each slide. These were selected at

random; thus an equal area was studied on each slide, so that direct compari-

sons could be made. Fach microscopic field was approximately 0,021 mm2 in

area, so that the area counted for each slide was approximately 0.21 rm2,
For certain purposes, the two slides taken from each station were averaged,

as seen below,

The stations chosen at Silver Springs for the study were chosen for

presumed differences in productivity, Two stations are reported on here,

one (5) near the main boil of the spring, with a relatively strong current
and with much light present. The second station (12) is located in a side

pool, away from the main current, which has little current and as it is
under a projecting tree, relatively little light,

In order to best illustrate the differences between the stations, grap-
hing the counts (cumulative individual numbers) against the species density
(cumulative number of species) was done by the method of Vestal (1949) with

some differences. Vestal's, Oosting's (1953) and others curves are species-

area curves, whereas equal areas were compared here and the curves are

species-individual curves. Rick and Kelting (1955) noted that Vestal's use
of a semilogaritlmic (areas placed on a logarithmic scale) species-area

curve may be of real value for adequacy of sampling, Rice is at present

attempting to clarify this statistically (Rice and Kelting, 1955). Here

it is assumed that this technique is valid for species-individual curves
considering that, in all cases, the area counted was the same. Time did
not permit a statistical test of its validity, but one slide was studied

in which the slope was the same after 10 fields were measured and after 70

fields were measured (9,9t4 individuals).

Results

Figures 1 through 6 show the species-individual curves obtained from
counting 10 fields on each of two slides per station from two stations -

the highly productive area or near boil station and the low productive area
or side pool station. The quantity of chlorophyll, also in these figures,

is, in addition to total numbers, presumably a valid measure of the quantity

of organisms and therefore of overall productivity. The effect of time is

also evident in these figures, which illustrate slides taken from the water

at various intervals, from 7 days to a maximum age of 93 days,

Figure 1 shows that, at first, slides from the two stations are very

similar as regards the species-individual curves. At 7 days of age, there

are many species and few individuals at both the rich and the poor stations.

Figure 2 (16 days) shows the beginning of a separation in the curves from

the two stations. There are still, however, few individuals and many species
at both stations. The chlorophyll quantity is beginning to show considerable

difference between the two stations also (0.128 mg. rich station, A@005' mg.

poor station).
Figure 3 (28 days) shows the first clearcut separation between the curves

from the two stations. The number of individuals at the poor station is

still low and the species density remains high. At the rich station, however,

the number of individuals has increased greatly and at the same time, the

species density has decreased. In this case then, the most critical period

at the rich station was .-11' ., ibly somewhere between 16 and 28 days for both

a considerable increase in nuwibers and decrease in species0 No such change

is seen at the poor station, which, up to 28 days, has remained rather static.

These changes which occurred at the rich station are reflected in the tremen-

dous jump in chlorophyll quantity, to more than 0.3 mg., whereas the chloro-
phyll quantity at the poor station has remained below 0.01 mg.

At approximately 50 days of age (Figo a), the separation between the

curves from the two stations is further increased, again the poor station

remaining fairly static with many species and few individuals, whereas the
rich station continues to be dynamic with considerable increase in numbers
over Fig. 3 and with considerable reduction in species density, The chloro-
phyll difference between the two stations is still very great, although the

quantity at the rich station is less than that at the same station at 28

days of age (Fig. 3). This is perhaps at least partially explainable in this
ways the slides rE r o,:c:: ctc by Fig. 4 (rich station) were taken up on the
8th of September, probably entering into a period of less light with the

approach of Autumn, whereas the slides represented in Fig. 3 (rich station)

0.3

*

So oc +
x x

t i-

00
x
X

0 -.0
o

I I Ioe

Figure 1. Diatom species-individdtal curves from slides left in Silver Springs, Florida, for ? days. Chlorophyll
quantity (average of 2 slides from each station) is indicated by the histograms (solid:side pool station; clears
near boil station). $ s slide 1, near boil station; slide 2, near boil; x= slide 1, side pool; 0z slide 2,
side pool).

0 4

a
A ;*

X

0 t-_ !

10

Figure 2. Diatom species-individual curves from slides left in Silver Springs, Florida, for 16 days. Chlorophyll
quantity (average of 2 slides from each station) is indicated by the histograms (solide=ide pool station; clear
near boil station). 3 slide 1, near boil station. = slide 2, near boil; x = slide 1, side pool; 0= slide 2,

side pool).

4 1 *

X
0 0 0

o10O0

I

iz.
i
i
i-

a
ic

ox
OX 15
0 Xx
0 X
0 /

0 x
X

4 -- -+ +

Figure 3. Diatom
quantity (average
near boil station.
side pool).

lex.. (I'x ediuaInose Iftt 1i-aT ve.l

+ + +

oo00

species-individual curves from slides left in Silver Springs, Florida, for 28 days. Chlorophyll
of 2 slides from each station) is indicated by the histograms (solid-side pool station; clear
4 slide 1, near boil station. = slide 2, near boil; x a slide 1, side pool; Oslide 2,

4-

aI-

'-

LOJ

- I-C~- I-~-- ~--- -- ---------

O00

0

1-* 4- -
*+
t

yp f t k
jr54 Htid rir,.'ef *',( litn rtlalrr/l:
Figure 4. Diatom species-individual curves from slides left in Silver Springs, Florida for 49 days, near boil and
46 days, side pool. Chlorophyll quantity (average of 2 slides from each station) is indicated by the histograms
(solid a side pool station; clear a near boil station). a slide 1, near boil station; slide 2, near boil x a
slide 1, side pool; 0 a slide 2, side pool.)

________ .1. .t .J-~-~----i--------

.4 .

were taken up on August 18, still in the Bsun ..er.

Figures 5 and 6 emphasize a continued. c.hage at the rich station as

opposed to continued fixity at the poor statii'o in r' E;i :1 to the species-

individual relationship At the rich station, the species density is fur-

ther reduced, with a continued increase in numbers in Figure 5. Figure 6

reveals a decrease in numbers over Fir- 5$ at the rich station, but the

dominiaint species changed between the two. After 61 days at the rich station,

a s.ill species, Achnanthes lanceolata was the dominant species; whereas

after 93 days, Cocconeis placentula. usually con-siderably larger than the

fornier, was the dominant form. Thus, t.-t.l. :-. numbers were less at 93 daya

the volume of the individuals was.perhaps no less The chlorophyll quantity

has increased at the rich station at 61 days (Fig. $) over 49 days (Fige 4)

whereas at 93 days (Fig, 6), it is far lo-e-r tian at aost previous deter-

minatiorns The latter situation is :rc, ~ r.." cJ :. :-". e:cplainable by the lesser

light in Autumn (October 22). 2.- difference in chlorophyll between 49 and

61 days is small and perhaps merely individual variation, and thus perhaps

without significance.

At the poor station, again the numbers arnain lcw, the species density

high and the chlorophyll quantity low at both 60 s_- of age (Fig. 5) and at

79 days of age (Fig. 6), Differences in c ..1.: ., 11 quantity at the different
ages are so slight that they appear to be merely individual variation, eesa

though there is a tendency for reduction in chloropyll with the approach of

winter (Fig. 6, poor station, represents slides removed on November 10, 1955).

It thus appears evident as illustrated in Figures I-6, that two factor

are of prominent importance in the species-inditidual relationship: time

and productivity. This conclusion is furthe-r .-.'_l rl by Figure 7, which
shows thgeaverage total species-individual rla.ionhps for all slides and

stations considered in this rc.crio Althoiugh she:'e is vsariation in the pic-

ture afforded by this relationship, there i.: ;:"-. ly j dZstinct tendency

o

01

0 Xx

...L"W 20 I aiomspeciesolndividual ourves from lides left in Silver Springsp Florida for 61 days, near boil
60 days, side pool. Chlorophyll quantity (average of2 slides Afrom each station) is indicated by the histograms
(solid -side pool station clear a near.boil station) a slide near boil station de 2, near
slide 1, side pool; 0 a slide 2, side pooL.)

i

"If

and
ii

lxs

I If

la, nd1rv"1 RA.A no046utWtmA ivr I

r-4 .,,M,,, NA -- -

'3

CIO

/o o

I O-

i
S-^m^-r-1-1 I i ---_ {- -^ ^^--- ~- -, IOQ
*. IcIdIvtI t WI OSkmutait.f irlifte
Figure 6. Diatom species-individual curves from slids left in Silver Springs, Florida for 93 days, near boil
79 days, side pool. Chlorophyll quantity (average of 2 slides from each station) is indicated by the histogram
(solid a side pool station; clear a near boil station.) a slide 1, near boil station; *u slide 2, near boil

ij

I

1=

{fh
i
}-r

.

.r..r

t
t:'

anda

3 r3

Ixm

slide I, side pool; 0 m slide 2, side pool.)

for the species density to decrease while the individual numbers increases

only where enough time has elapsed to permit such a change to take place,

and in this case, where there is relatively high productivity. Of course,

it may be that eventually such a change might take place at the poor station,

but that remains to be seen.

Figures 8 and 9 further illustrate the relative fixity of the organiss

at the poor station in regard to species per cycle, numbers of individuals
and chlorophyll quantity; while Figs. 10 and 1 illustrate the relative

dynamicity of the organisms at the rich station in regard to these factors.
Discussion

As a result of the data and ideas accumilated from this study, attempts

to classify all factors which influence the. n~jber of species in an area
have been made. Two principal factors appear to o this, the history of the

area and the proximity of the area to the general optimum. Under the former

are placed isolation, vew species formation (genetics) and the time factor,

age of the substrate of of the medium. Under proximity to the general opti-
mum are included various environmental factors, both abiotic and biotic,
such as temperature, wter, chemicals in solution, predation, competition,

etc.

The history of an area influences the n1mbor of species present, in that

species which could 1e in the area may not have been able to get there.
Isolation is:>therefore undoubtedly of importance in many areas, especially
among those organisms ith poor means of distribution. If new species are

formed in an area, they will obviously influence the number of species and

therefore genetics is also a historical factor to be considered.

The time factor appears to be of more importance than the other two

historical factors. A certainn amount of time is required for organisms to

occupy the slide, or in the case of "young" ate'~cr (Steemann-Nielsen, 1954),

a period of time is necessary for pioneers to : vado a water mass. Therefore,

79
' i

water., /a near boil station;*. side pool'station.
./'d

t .I

1

water. d nsay boi station: ~ ide pool station.

r

tion
n the

u

U

U

Figure 8. Relationshipof the number of species per cycle (below)
to chloropkyll quantity (above) and time, side pool station.

5 d& -Pool S ia-IOt.

i i

i i

iF

i
ii

fI

wYelda.- t)

u

LI-

i AA-t a 1 4

_ -- 111 0 I --- -~.. - --- -- -- 0 -- --- -, w -M

M *AMER=r

- I

.1-

:

sde. Pool Sra. tor

Figure 9. Relationship of the number of species per cycle (above) to the
number of individuals (below) and time, side pool station.

*

1i 1
:; I

Y)o.aR BoI Sria.an

ew

[1

9
i ':

i ii j
J l l ll

Figure 10. Relationship of the
number of species per cycle
(below) to chlorophyll quantity
(above) and time, near boil
station.

F-

CIt
*1d

1 1 I

41
I

-l b

6 n.

n ii
I'i
1~

ft P ft

Ii

-.T --- ik -- -- -as 4A 61--;~in- ~ ~ ir U~-CIR1 ----I------I-- ~- -4

Figure 11. relationship of the num-
ber of speaMs per cycle (above) to
the number of individuals (below)
and time, near boil station.

VNLo.N Dod srrTIrDn

Ati
100r

1t

I

U

S Z
On
c5)

6
k
7iZ
rP
r0
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k
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f`L
lr,
t~A

r~
sa

ji

-" "Olld~lr) 17

Wt

Z3

n =

t 7 )w

according to whether the organisms are benthonic or planktonic, the age of

the substrate or of the medium would affect the number of species present.

Time is a successional phenomenon as illustrated in the figures, and is im-

portant in succession in combination with other factors, especially produce

tivity, as discussed below.

Proximity to the general optimum has perhaps the most important influ-

ence on the species density of an area, since whether species are able to

live there is determined by this proximity. In attempting to define this9

however, great difficulty is met with because of the numerous factors that

contribute to it. The general optimum can, however, be defined as the en-

vironmental conditions under which the majority of species on the earth live.

General optimal conditions therefore would probably have to be looked for in
the tropic marie tr ane environment, inasmuch as a larger number of species prob-

ably live under conditions there than anywhere else. But when the insects

and terrestrial plants are considered perhaps the terrestrial environment

more nearly approaches the general optimum than the aquatic. At any rate,

the only way to measure it appears to be to determine the number of species

that are able to live under its conditions.

Among the conditions which may be considered in a discussion of the

general optimum are two chief types, abiotic and biotic, Abiotic factors

which must be considered to influence species density are numerous. Two

might be used as examples, temperature and pH in their relations to the
blue-green algae of the Yellowstone area (Vou,1950). Vou~ reported that,

at 10CoC, i species of algae were found; at 350C., 90 species were found;

and at 8Cc,, only 6 were found. The optimal condition in regard to tempera-

ture for these algae in this area is therefore at about 350C. -- how close

this approximates the general optimum, however, is uncertain, Similarly, in

regard to pH, more than 90 species were able to live where the pH was about

8.3 whereas at 9.5, only 23 were able to exist, and at pH 3, only 2 species

were found,

Biotic factors which influence species density are also varied, and

equally as important as abiotic ones. Competition, for example, apparently

has considerable influence on species numbers: species numbers are appare-

tly less where competition is great than where it is negligible, as illus-

trated in FigS. 1-7 of this report. Predation or grazing presumably could

eliminate one or more species from an area if great enough, and a lack of

it would permit these species to exist Harvey (1955:23), for example,

mentions that Phaeocystis is not eaten, and so would be represented in a

floral list where grazing might eliminate others.

When we consider the species density of an area, it is necessary to

delimit this area. It would be better to use the term habitat, as in one

area, many habitats may be present, each with its own characteristic species.

Obviously, if there are animals in a tree at 100 feet and others on the ground,

the species density will be greater because of the presence of the two habi-

tats than if there were but one. In determining the factors that influence

species density, therefore, it appears essential to consider only one habi-

tat at a time.

In each habitat, there are a number of niches (Elton's definition 1927)
filled by various species; the number of niches apparently also would affect

the species density, so that this seemingly should also be considered, For

example, if in one habitat, there are 5 species of herbivores and 3 carnivores,
and in another, 5 herbivores and one carnivore, it would seem better to make
the comparison by graphing herbivores against herbivores and carnivores against

carnivores rather than species against species, in total. I think, however

that where one trophic level is affected in species numbers, all other levels

are probably also affected, For example, if 10 species of salps are found
in an area with 5 carnivorous species of plankters and in another area only

one species of salp is found, probably also fewer species of carnivores

would be found inasmuch as both groups would be affected by the same conditions.

Therefore, .the niches of the various species in a habitat possibly need not

be considered in a comparison, but only a species-individual graph.

An important factor in determining the species density of an area, which

also should be placed under the heading of proximity to the general optimum,

is productivity, Prinary productivity is defined by Odum (1953:78) as the

rate at which energy is stored, by photosynthetic or chemosynthetic activity

of producer organisms, in the form of organic substances that can be used

as food, Consumer or secondary productivity is dependent on primary produc-

tivity, so that all parts of a trophic system are affected by the primary

productivity. Productivity is therefore dependent on biogenic factors avail-

able to the producer organisms in a habitat: the enery source, light; water;

materials in solution used in building these organic compounds, such as phos-

phates andnitrates; etc. In addition, productivity by its definition is de-

pendent on time

As regards its affects on species density, productivity affects density

of the organisms which in turn, affects the numaibor of species in a habitat

as shown in Figs. 1-7. The near boil station, or highly productive one,

shows that the density is great in a short til, T'hich is reflected in the

large numbers and few species. The station with lov productivity, however,

shows a varying slight but gradual increase in rmuIber:s with time (although

not a reduction in species up to the present), and presumably eventually mra

become dense enough to show a species reduction. At present, however, it
remains in a subclimactic state, and under the present conditions, may remain

in this state indefinitely.

Competition, or perhaps better, coaction, is probably lesser in habitats

where there are many species but few individuals present, than where there

are great numbers of few species, as indicated in Figs. 1-7 A new habitat,

for example a microscope slide, becomes occupied gradually by all the species

of an area that can get to it and are able to live on it, Even in a highly

productive area, at first there are few indivi : tils of these many species.

As density increases, due both to outside additions and reproduction of in"

dividuals in the new habitat, the frequency of encounter increases gradually,

and as a result, those species better adapted to the conditions of this new

habitat become numerous at the expense of those less well adapted. In the

case of an unproductive area, however, inasmuch as density remains low the

frequency of encounter also remains low, permitting relatively many species

to coexist, presumably indefinitely It therefore is reasonable to presume

that where productivity is great, competition is also great and the number of

species present is small with large numbers of individuals. Conversely, where

productivity is low, competition is probably pb roportionately low merely be-

cause of fewer contacts between organisms in the same amount of space, as

there are fewer organisms present, and therefore the number of species should

be proportionately large. Thus, the variety of species apparently depends

on the frequency with which different species encounter one another, Fre-

quency of encounter evidently applies as well to sessile organisms as to

vagile ones. If the number of individuals of all species present on a slide

increased considerably but the species density did not change, the slope of

the species-individual curve would remain high although it would move to the

right. If certain species were eliminated while others increased in numbers

the slope would bend toward the abscissa and away from the ordinate, as is

the case only in the graphs determined from counts from the highly productive

station. The slopes determined from counts from the low production station

remain high, nearer the ordinate, These appear to reflect in turn the amount

of competition as a result of the differences in productivity.

It is concluded from this study that there is, in any habitat, no one

factor which determines the species density of an area, but always a combina-

tion of factors, It is obvious that time and productivity must work together

to have effects on the trophic systems, and that other conditions affecting

the organisms of the habitats must also be considered for valid use of

comparisons of species density between two habitats. Thus, the conclusion

(Patrick, et al, 1954) that pollution eliminates the more sensitive species

from a habitat and compaction is therefore reduced, and that in rivers not
adversely affected by pollution, conditions are favorable for many species

and competition is great; may be somewhat premature. If their conclusions
were used, Silver Springs (highly productive station) would have to be
classed as a "polluted stream" and the station with little production in

Silver Springs would be classed as a stream not adversely affected by pol-
lution, It shouldd seem. more correct to presumei that pollution has at least

two effects, the one to eliminate sensitive species, but since biogenic
substances are added by pollution, the pollution is probably also simultane-
ously increasing, rather than reducing, competition.

References
Boyer, C. S. 1916. The Diatomaceae of Philadelphiaand Vn it. 1l3 pp.,
40 pis. 'o B.Li ppincott, PhN-la ...

Brooks J. L. 1950. Speciation in Ancient L. Quar Rt. .. 25(192)
30-60; 131-176.
Elton, C 1927. Animal Ecology. 209 pp. Sid[wick & Jackson, Loono
Harvey, H. W. 1955. The Chemist & Fertilt; of S o Waters. 224 pp., CaS
bridge Univ. 'Press, Cambridge
Hesse, R. 1943. Tierbau und ierleben, 2nd ed., vol. 2, 828 po Gustav Fischer,
Jena.
Hustedt, F, 1930. Bacillariophyta (Diatomeae). in Pascher's Die Susswasser.
Floral itteleurpass Heft 10:1-466o
Odum, E] P. 1953. Fudamentals of Ecolo 384 pp. We B. Saunders, Phila.
Oosting, H. J, 195$. Plant Communities. 389 pp. U. H. Freeman, San Francisco.

Patrick, R., M. H. Hohn and J, H. Wallace, 1954o A new method of determining
the pattern of the diatom floral Notula Nfatuae, Acad.Nat.Sci.,
Pil.e noo 259lt1-12,
Rice, Eo Lo and Ro Wo Keltingo 1955o The species-area curved Ecology 36(l)7-.ll

Richards, F. A. and T. G, Thompson, 1952o The estimation and characterization
of plankton populations by pigment analyses. II. A spectrophoto-
mietric method for the estimation of plankton pigments, Journa of
Marine Research, XI(2):586-172,
Smith, Go M. 1950. Fres ywate A. gae of thJa Uted States. 719 pp. McGraw-Hill,
New York,
Steerann Nielsen, E. 1954. On organic production in the oceans. Cons Perm.
nt.xor Mer, Journ. du Cons. 19(3) 309-328.

Tiffany, L. H. & MI E. Britton. 1952. Th aeofIllinois 407 pp., Univ.
Chicago Press, Chicago.
Vestal, A. G. 19L9e Minimum areas for different vegetation oIllinois Biologi-
cal Mononraphs XX(3):l-129.

Voouk, V. 1950. Grundriss zu einer Valneobioloe der Tlermeno 88 pp., Verlag
Birlhauser, T3asel.

STUDIES 011 PRODUCTIVITY IN SILVER SPRINGS: COMPARISONS

WITIH 10 OTHER SPRINGS

Howard T. Odum

New work during surlmer 1955 and analysis of previously obtained data

were incorporated into a finished manuscript on Silver Springs (see list

of publications and reports), The fu3l details should thus be available

in the form of a published paper for the final report. Methods of measuring

primary production developed in Silver Springs were applied with the able

assistance of James esscrly to 10 different and varied Florida Springs.

Some of the new results are given below Other results will be included

in the final report.

Chlorphyll and ag.nic atxtter or0

In previous reports, efforts directed at estimating downstream export

of organic matter have been sizuxarized. Two new series of BOD measurements

this summer again produced anormalous results. Although the interpretation

is not clear, it seems impo;acible to conclude that there is a large down-

stream export of di soledd or total organic matter although evidence is ir-

refutable that particulate, pseudo planktonic organic matter is exported A

re-axamination of the balance sheet again raises the question as to the re-

liability of bell jar estimates of respiration in a community where water

normally flows through the algae and plants at a rapid rate, Since a higher

value of respiration was obtained from Sagittaria-aufuchs in a flowing res*

pirometer than in bell jars, these two sources were averaged. It was thus

possible to balance the community income and export

Chlorophyll determinations were made on the benthic community, various

parts of the eel grass at measured distances from the base and on the mille-

pore concentrations of floiArg water, A diurnal curve of chlorophyll in the

water at the 3/4 mile station in Figure 1 below indicates a diurnal pulse.

S------

i12 2 4 k

Fiqupe I. ChloiopAyll// in OT-eia ,;rt e 3/ m/le
S-r A.o T i T m / Th12 /Q I55'
1/

Because of the diurnal activity of the glass bottom boats, it is not possible

from this spring to definitely assign cause to diurnal pulse in algal growth

or to boat disturbance or both, The chlorophyll in the dense benthic com-

munity, although large (2Y9$5 gr/V2), is of the same order or magnitude found

for many other kinds of naturally adapted communities by Gesaner (1949

Schweizerisch Zeitschrift fur IHydrologie 11:378-410). The chlorophyll is

most concentrated several inches back of the tips and thus below the level

of maximum light intensity nud in the region of the eel grass blades where

most rapid algal grorwh is ocuring.

Photosynthetic Quotients in. Silver Spring

Two new diurnal ciunres of oxygen and carbon-dioxide (pH determined) were

made in summer 1955 on Silver Springs and combined with 8 previous values to

obtain a better picture of annual production and to estimate the nature of

this production from photosynthetic quotients. In Table 1 (Table 10 from

the manuscript cited in the list of publications and reports) given below

are the calculated photosynthetic quotients which were obtained from the

ratios of areas under the diurnal curves. The best interpretation of the

higher summer values sugoAstL protein metabolism dominating when the sun

shines most strongly and only carbohydrate metabolism on heavily cloudy days.

Precedence for this interpretation is provided in experiments by Myers (1949;

in Franck, J. F. and W, Eo LoomITs Photosynthesis in Plants, Iowa State Press,

ppo 349936),.

Table 1

Photosynthetic Quotients and Production in Silver Springs

Location, clouds

Photosynthetic
Quotient

protein

02/002 by
atoms

Nov. 28, 1953, broken
stratocumulus

Dec. 3, 1952, clear be-
coming overcast

Jan. 7, 1954, clear
Feb. 19, 1953, broken
stratocumulus

March 8, 1953, clear

(1,0)

(io)

production of
organic matter
(ash free)

gm/m2/day

8.0

6.6

0

0

0

1000

L2o9

h

March 26, 1953, clear

May 23, 19549, few cumulus

July 10, 1994, broken
cumulus

July 12, 1955, nimbostratus
and rain

Aug. 11, l955, clear

WINTER

SUMMER

1.3

31

(1.5)

12.9

23.4

16,0

11,3

13.7

0

77

primary Production in Ten Varied Sprin. s and a Marine Turtle Grass Bed

In Table 2 are given the results from measuring the primary production

in ten Florida Springs by the upstream-downstream measurement of oxygen and

carbon dioxide through a daily cycle R presented are sunny and cloudy days;

anaerobic and aerobic springs; oligohaline and non-oligohaline, hard water

springs. The high production in the oligohaline springs in spite of low

phosphorus and nitrate concentrations is not yet understood. These nutrients

may not be important in these flowing waters, Shade and depth of plant. beds

may be the most important factor in production0

The upstream-downstream method was modified and adapted to a bed of

marine turtle grass (see Table 2) by the use of dye spots to mark masses of

water flowing over the beds, Duplicate oxygen samples were taken at twenty

minute intervals adjacent to a dye spot followed across the grass bed.

Nitrogen Metabolism S

Another series of nitrate nitrogen detern;inations in anaerobic Beecher

Springs, Florida1 again indicated nitrate increase in going downstream sug-

gesting nitrogen fixation by the dominant blue-green algae. Thus nitrate

decreases downstream in aerobic springs and increases in anaerobic springs.
Boat Basin Exoriment

An isolated shallow water basin receives Silver Springs Water and holds

it long enough to develop a planktonic community0 This still water was used

as a natural experimental comparison with the flowing water. Light absorbed
in the upper meter was compared with the oxygen changes in this layer as

converted into primary production estimates by the diurnal curve method

An efficiency of only 1% was obtained in comparison to efficiency of 5% in

Silver Springs. (Silver Springs productivity estimates of 8% have been re-

calculated at 5% because the average depth of the plants seems to be 1o8 m
rather than 2.5m as previous~ estimated0) This comparison is evidence for the

hypothesis that stream flows are more productive than aquatic communities in

Table 2

Primary Production in Florida Springs in 1955

Night'values Photo- Oxygen a
0C Oxygen synthetic Production
J.i mg/lo Quotienta gm/m2/day
Green Cove Springs, July 7, broken cumulus,
shaded by trees partially 1,8 2,8 1,0 u11

Rainbow Springs, Marion Coo August 16,clear 3.8 5$2 1,8 33o3

Weekiwachee Springs, July 26, scattered
cumulus becoming overcast 4.8 1.3 1.6 97
Beecher Springs, W elaka, Aug. 2, broken
cumulus becoming nimbostratus and rain
heavily shaded with trees 4.5 .8 .73 .66

Alachua Blue Spring, Main Boil, July 28,
broken cumulus, partly shaded with trees 6.8 4o2 .84 U.7
Alachua Blue Spring, isttricularia Boil,
July 28, broken cumulus, heavily shaded
by trees 7.5 3.9 o76 1.8
Chassahowitzka Side boil (oligohaline),
Aug. 3"4, broken cumuls 9.2 3.8 1.28 24.3
Blue Springs, Volusia Co., Aug. 9,
scattered cumulus 7.9 .25 .58 o.9
Homosassa Springs, July 19, broken cumulus,
showers (oligohaline) 4.9 4.3 088 580

Manatee Springs, Augo 15, scattered
cumulus, shaded by trees 13,2 1,8 o51

Boat Basin at Silver Springs, July 20,
overcast, middle and low clouds 40 6o2 6o5

Marine Turtle Grass bed in 3 ft. water
Long Key, Fla., Aug. 14 Odum and
Young few high clouds only '-- 4o2 34o2

a Uncorrected for diffusion changes between day and night0 In Silver Springs this
correction is about 10%.

more stationary water, It dos not, however, indicate whether unlimited

nutrient supply of the flowing water or the current per se is the causal

mechanism of greater production.

Regional 10D

In 1955 a sustained drc::ght of two years was being felt by a lowering

of the spring flouru of ahor ,t 20,;' Correlated with this was a decrease in the

oxygen value of the outflow from about 2.5 ppm to 1.7 ppm and suggestions

of an increase in 002 value, These changes did not apparently affect the'

community in any detectable way, However, this change might be a reflection

of constant BOD demand of the legion aroimd Ocala, Florida which was con-

centrated in a smaller vo. m of water, When more is known about the source

of Silver Springs water it might be possible to convert this oxygen change

into a measurement of the underground decomposition rate of organic matter

in a sub-tropical land ai.ea

TMCROPIYTIC COI)iUNITIfES IN FLORIDA INLAND UATER~
Delle N. Swindale

Lae study of community composition of large submerged aquatic plants

in some Florida springs and runs was reported in the Second Annual Report

of this project ( pp. 20.3.). Tlis work was continued through the spring

of 1955 and extended to other inland waters of Florida which differ from

the springs chiefly with reard to chemical composition and temperature

stability of the wDater. Emphasis was laid on communities in freshwater

spring pools and their runs, lakes, and ponds but a cursory examination

was made of some r'iveB~rs loughs, and brackish waters in order to ascertain

the vegetational rela ionships among these various waters.

The sampling methods nero the same as those described in the previous

report with slight iHdiZfiations in stand selection for lakes and ponds.

In all types of waters a stand was an area which was homogeneous in depth,

substrate, and vegeteaicon. Frequency alone was used as the measure of com-

munity composition becaD(:e the additional infonnation contributed by density

or dominance measureents mas not expected to justify the time required for

such work, In recomnais anllo work of this type, the necessity of surveying

a large number and variety of stands demands the sacrifice of a certain

amount of detailed study.

Treatment of Data

The data was analysed in two stages: First, the data on the mutual

occurrence of species was used to reveal their community relationships.

Then environmental information was used to corroborate and provide some ex-

planations for them,

This work was supported by the University of Florida through a Post-Doctoral
Fellowship, with additional support from this project,

A. Joint Occurrence Index

Because the number of species in most stands is small and the variation

in species among stands is great, a method involving association between

species pairs, rather than a direct comparison of stands by their total com-

position was used. An index for the joint occurrence of each species with

every other species was calculated from the stands for which satisfactory

quantitative data was obtained. This index was the number of stands in

which each pair of species occurred together expressed as a percentage of

the number of stands of occurrence of the less ccnmon species was used in

order to avoid a low jcinat occurrence index for two species merely because

one occurs infrequently.

Species of pairs with zero joint occurrence were placed at opposite

ends of a list, the order of which is believed to be a reflection of plant

reaction to the complex of environmental factors. Species of pairs with

high joint occurrence ;ere placed near each other. Eventually the species

were listed in an order- which reflected the association tendencies of all

the major submerged species in the waters studied.

If this order is true to the natural ecology of the aquatic plants in-

eluded, its application to a classification of the communities they compose

should result in a natural order of communities, In order to weight the

species according to their position on the list, it was divided into ten

groups of species as sho4n in Table 1I and each group was assigned a number

which is termed its ecological adaptation value (E.A.V.), The list shown

below is not the original one but the result of several preliminary attempts

at classification which elucidated the position of some of the species.

Table 1. Ecological Adaptation Values (E.A.V.T) of Taxa studied.
Taxa ERA.V.
Tleocharis Baldwinii (Torr.)Chapm. 1
Utricularia esuginata BD,. Greene 1
NsTtepa'p or .p 2
itaria sp. or sppo 2
Eriocaulon sp, or spp. 3
tried carolniana (Walt,)Small 3
SsppO 3
U- olivacea Wright 3
fro~'~e ing sedge 3,4
U. foliosa L. 4
13 Turia Walt. 5
e on ata chajmi. 5
e- d '^'4ds C ipm-o 5
o i eteropyllum Michx $
cotyle umbellata L 7
oninalis sp. 7
Nastuium officinale R Dr. 8
Ludi a inatms i ..110 8
Chars spp. 8
74p Spadalpu si 9
qera ohellum deiersum L. 9
iiao~u 1n ilTSens Morong, 9
S ittaria lorta iChpm)Small 10
isnerij a sp, 10
SnectinaTus L. 10

Bf.. Arrangement of stands according to sp~ci c oe position
The relative frequencies of the species in each stand were weighted
by their ecological adaptation values, and the sum of the products was used
as its continuum index (C.oI,) The term continuumu" is used here even though
a continuum has not yet been shown to exist in the vegetation under consider.
action, However, the continuum-formulation procedure which was used is one
which would reveal a continuum if. 1 t.d d but it would alos reveal discrete
communities if they exist, A sample calculation follows:

ies Frego () % Rel. FregVj E**.V* Rel.Freq, x E.A.V
Najas guadalupensis 80 34o0 9 306.0
Potamogeton pectinatus 75 31.9 10 319.0
Ceratophyllum demersum 65 27.6 9 2L45
Vallisneria sp. 15 6.) 109
9999 = C.I.

The stands were arranged along the abcissa of a graph according to

their continuum indices, which ranged from 100 in stands which had only

species with E.A.V. 1 to 1000 in stands which had only species with E.A.V. 10.

The relative frequency of each species in each stand was plotted on the graph

so that the range of each species in the entire aquatic plant range (considered

in this work), and the frequency with which it occurs in its range could be

seen. The presence of several dominant species with superposed curves would

indicate the existence of a discrete community unit. Overlapping curves,

however, would indicate a continuous transition in community composer ian

along the ecological gradient or gradients (i.e., a vegetative continuum).

Both of these conditions occur in the waters considered here, but the latter

is by far predominant.

Results and Discussion
Two groups of stands are revealed, each of which contains a group of

species The two groups of stands contain no dominant species in common and

in this respect may be considered separate cormunitieso Only one lake studied

had stands with dominant species belonging to both groups. Because the intero

mediates are so uncommon it is practical and simpler to discuss the aquatic

vegetation in terms of the two groups, and consider their interrelationships

later. One group includes all the ponds, small lakes and most of the larger

lakes studied. The other, which includes spring pools and runs, and saoe o

the large lakes, will be discussed first.

A. S rin s t their runs^ d e lakes (Sitands wihC Figure 1 shows the graph constructed for this group of stands Because

there were often several stands with the same Cl,, the abscissa was divided

into units of ten and the relative frequencies of the species in stands within

each unit were averaged and charted at the unit midpoint. The number of stands

represented at each midpoint is shown on the graphS Th&ifis a great variability

among stands which is related to the low number of species per stand, the

(

average being 3,7. The relative frequencies were, therefore, smoothed by

a moving average of five in order to emphasize the range of each species

and its average relative frequency within its range. A slight additional

smoothing by inspection was done for the sake of clarity.

Basically, this graph portrays a continuum. IJja and Ceratophyll

bridge the extreme stands and provide a continuity of vegetational change.

However, the partial superposition of the curves of urj Nasturtium

i o_ Fontinali s and Ghara is a reflection of their association in
nature. They are typical of the moderately calcareous springs and their

runs and are rarely found in the sane water are as as Vlisneria ,
natus or S *lorata-

Some of the springs which are inhabited by these species and/or as

are Ichtuclmee Headspring and Run, Fanning Spring, and IHar, Wadesborov

Wekiwa, Green Covej, and Crystal Spring Runs. A summary of the water ana3ly

ses for these springs, as well as for other waters which will be discussed

below, is presented in Table 2.
In these springs and runs, as in those which were discussed in the pre-

vious report, different communities often occur within small areas, even at

the same depth. Frequently, an environmental correlation is obvious, e.g.,

different substrates. However, in other situations no reason for the dif-

ference is apparent and it is possible that historical factors such as dise

turbance, availability of propagules, and conditions conducive to clone for-

mation were largely responsible for the non-uniformity. There is also a

strong possibility that more detailed study would reveal significant en-

vironmental differences. Ludwigia, for example, was found in the areas
with high organic content substrates more often than were its associates.

The trace of Ludwigia's curve in Fig. 1, extending its importance into

higher C.I. stands, reflects this tendency, for as will be explained below,

the transition of stands from C.I. 100 to C.I. 1000 parallels the transition

from oligotrophy to eut)irophy.

i l

Table 2. Summary of the results of available chemical analyses of the water
of springs sampled in this study. The results were taken frm Florida
State Board of Conservations Uater Survey and Research Paper Noe 6,
November, 1951. The minimum and maximum quantity for each factor
in each group is listed below.

Factor

Stands with C.1. 700 875,
including stands in
Ichatucknees Fanning, Hart,
Wadesboro, Wekiwa, Green
Cove, and Crystal Springs.

Total dissolved solids
Silica
Iron
Calcium
MNagesium
Sodium and potassium
Bicarbonate
Sulfate
Chloride
Nitrate
pH1
Total hardness as CaCO3

110-200
5$.2-13
tr-0.08
28-67
1*7-15
2.4-$.4
102-210
3.041
3.6-11
tr.-2,3
7.3-778
89-186

Stands with C.I. 874-1000,
including those in Poe,
Alexander, Silver, Salt
Silver Glen, Chassahowitska,
and Homosassa SpingSo

2104580
7.8-11
.03-.12
4l-240
6,4-167
L.6-1563
85-204
13-613
6.8-2800
.03-1.3
6.9.7.8
176-1290

70

Ow%

4*4

No0 l et b~s

ragittairt
lorava

4-sk

r '~

4:,,
V V

Hydroeotyle nob /,

Ilaeistpuua- o'f0lao

1. ,,"_"1"~P~"i"~"
I- S

OCnl 700

.. ,/
r'~ 'i'"tin

80
4' \ .
a1.....gtxTTTY-$

8wco

F:Irae lo Relative frequacn f ..j~' ~u;pier in efztophic stands.

i/if

~*ZI:us~rr~JP~WsrspIU*ra~~CHYCI(l(mUD U.l

QIWIY~Uu4RII*I~L~PW1~rrrrxmu^-ul~-l---- -e ----~ -Y

i

rSbaa~Lrmra:Lr

The dominants of the most eutrophic stands, S l V allineria, and

P e atinatus occur alone and in combination in springs and runs of hard or
brackish water, and in certain large and/or spring-fed lakes. They also occur

raixed or in the same body of water as Najas and Ceratophyllum. Some of the

springs in which these species are dominant are Poe, Alexander, Silver, Salt,
Silver Glen, Chassahowitzka, and Homosassa. A sumnary of their water analyses

is presented in Table 2.

A comparison of the analyses for the two groups in Table 2 reveals that

they can be separated on the basis of the chemical composition of their
water, The content of total dissolved solids provides the most clearly de-

fined difference for there is no overlap in this character. The second best

correlative character is total hardness as CaCO3, which is 89-186 and 176-1290

for the two groups. There is some overlap in sulfate, chloride, calcium,

magnesium, and sodium and potassium, but the tro-d toward higher amounts
in the higher continuum number stands is clear. There is evidence of a slight

trend toward more iron in the higher continuum stands but silica, nitrate,
and pH show no consistent trend. "Bicarbonate", which in these analyses refers

to total alkalinity (HCO3, OH, C03) in terms of bicarbonate, has a sightly
lower range in the higher continuum stands and a lower average as well. Those

springs in the C.I. 875-1000 range which have low alkalinities are also those

which have high chloride and sulfate content (Salt, Silver Glen, Homosasoas

and Alexander Springs).
The previous report on springs vegetation treats some of the environmental
relationships of the species in this group and these will not be repeated

here, Instead the present report will interpret the results presented in the

former one in the light of subsequent work,

The regular trend in vegetational change downstream which was noted in
Chassahowitzka and Weekiwachee Rivers (p. 22 of previous report) is well

correlated with the continuum, Weekiwachee River at its source has fresh

water of a quality similar to that of the stands .-it 1 C.I, 700-800, The

river becomes more saline as it appraabhes the Gulf, Chara, which was abundnat
in the upper part of the river, has a curve which peaks near 800 on the continuum.

Ceptz ~ ump which also was abundant in the upper part of the river, but
which extended much further downstream, peaks near 900 on the continuum .
Nj which was most important in the middle section of the river, also peaks
at 900. pectji tusand JValisnerlya which peak at 1000, are restricted

to the lower part of the river. The fact that S. lorata was more abundant

in the upper part is in agreement with other observations that, although

. l rata and Vallsneria both grow well in waters of high carbonate hardness,
Vallisne.zria has an advantage over S. ittaria in saline waters.

It should be emphasized that the order of species ong the continuum

does not imply a strict relationship with any one factor, such as hardness,
but a general relationship with a complex of aiviirorimental factors including
hardness, salinity, turbity, substrate qualities, and current

Therefore, it is not surprising to find Sagittaria poorly correlated

with Vallisneria in a river even though their curves occupy similar positions

on the continuum. In the Weekiwachee River, i iis probable that the salinity
of the water near the mouth of the river prevents the growth of Sagittaria
there. The reason that Vallisneria does not grow upstream with Sagittaria

may be one of history or substrate, but it also may be related to the taxo

nomic position of Vallisneria in Florida, which rLll be discussed in the
section on identification and taxonomy.
The vegetational trend in Chassahowitzka River is similar to that in
Ueclc:.achee River except that the water issuing from Chassahowitska Springs

has a higher mineral content than that from Weeldwachee Spring and S ra

is most abundant near the head, with NaJa, Vall. sn.ria and A pectinatau
reaching their maxima in the lower part of the river.

The intermediate character of Najas and Ceratophyllum is apparent from

Fig. I, but the relative superposition of the curves of Vallisneria, .lorat

and P. ectinatua require that a clarification cf their relationships be

-att.d to 0hof.; t, hat they are not g. c. .ivalnte

-The As of e-qlanation NV ith the nt of the continfUum as a

ro.flot o. Va, of an ecological comriplcx, j.hih : -2 it.: tlin.ar representative

an oa plifi'cationt Where one cx vircai..l gra.dien is predominant over

all tl. :' iers, however, a linear co.ntinur m ca be ie-:ed, for the stands will

: c::;:.:.. :. Ced, in general, witi T.h gr:adiesnt f the predomiant factor. The

Crater influence ,of trhe prdc in .. f.tor, the more obvious will be

the environmental correlations of the st nd, aS- the fewer the irregulari-

tieso In Florica., the predolialnLrnt environmJiiel. :infltnh ce is the mineral

contea-t of the water as reflected in tihe tr-ec2d fro.': cligotrophy to eutropbhy

SaLinity and organic dystrophy are two imprort;it :c-difyxg f actors

Data fom Weekiwachee, IImossass ChasXdli ::.tbsk and Salt Springs, and

their r~ r, as well as work done by others (Fl1:ri>a .crfc2.- Survey, F. A.
AJu ? lquq ablt ) i Flormtdc rehal arr
Project 19RP a pectinaus is better adapted to br.i h waters than alliner

. .... Th G 'The reaction of P. )mt r' todline conditions

l;as betil sbudied exerimentally by Dourn (L$2R :hoCr'ver in Florida,

Vallisneria and S. lorata replace P sect ,,n-C ar aa -s;iant in fresh water,

even when the water is very hard carbonatee I .r-"c : ) The narrow curve of

PO pectinatus in Fig, 1 is in agrecnent wth its l iitd -range in Florida,

It must be stressed that this does not apply to P. FctinLtus throughout its

ranges as it is often abundant in hard fres.u:~t. e in other regions

In fresh calcareous waters. allineria aod i oS, :lat seem to be inter*

changeable but it is possible that a detailed .Virn.: .'ntal study of the two

species would reveal slightly differing ecclogic:al prferen-ices. Silver Springs

Run offers a good field for an investigation into this problem because it is

dominated by Sittaria lorata, but Vallsneri is a codczinant at various

plaCBes and. in some places, exceeds S., loraa iUn import'ce, with no obvious

diffcu:::c. 2T, environment. The differences .r.. not so o" cure, however, where

salnry i afantr '-or as niod b7 ^ .E ^- slit

;.I- Lj W. I Vu

The superposition of the peaks of S. lort, sVallisneria and P pectinatus

then, does not imply a discrete community but presents a composite picture

of the positions of these species along several gradients. The two for which

the best data are available are salinity and carbonate hardness and they have
therorfore been stressed. These two gradients alone can be considered in in-

terpreting the CI., 875-1000 stands as follows: If only Florida's fresh
waters are considered, a status is insignificant, and Nas Sagitari

and Vallisneria would terminate the continuum at the eutrophic end. Jhen
saline waters are considered, Vallisneria replaces S. lorata with increasing
salinity, and is in turn replaced by P. ecinatus, as diagrammed below

l^x/f

The continuum in Fig. I was formulated from all the waters studied and
therefore merges the gradients and Sagittaria l o Vallisneria and P?

petinattsl all terminate the continuum, which is a generalized presentation
of the vegetation studied and must be supplemented with other data for accurate

details. It should be emphasized that P ectinatus only terminates the

salinity gradient as far as it was sampled in this work. As salinity increases
beyond that of the waters sampled, )Ca, m ~pia riim and eventually
marine algae dominate the vegetation,

Among the stands with C.I, 875-1000 there are six which are not strictly

part of a spring or its runm They include stands from Lake Okeechobee (near
Moore IIHaven), George Lake (near Silver Glen Spring), Crescent Lake (east aide),
Lake Panasoffkee, and the Panasoffkee River, and with the exception of the
latter, contain only species with EoAoVo of 9 or 10,

The water of Lake Okeechobee at Moore Haven, according to Water Survey
and Research Paper No, 6 (cited, Table 2) co:nt~a.d 182 ppmo of total dissolved

t

solids, similar to those of Ichtucknee and Fanning Springs, but its calcium

(30 ppm.), bicarbonate (84 ppm.), and total hardness (82 ppm) were much
lower than the corresponding values for the above springs, which were 58-66,
200-210, and 172-184 respectively. In spite of this, the C. Io of the stand

was 931, and this is apparently related to the sulfate and chloride content

of84 and 16, while those of Ichtucknee and Fanning Springs were 8.4 and 3-6,
and 9o9 and .0o respectively. While the saline content of Lake Okeechobbe
is far below that of the salty springs (Salt, Silver Glen, Homosassa), it
seems to be sufficiently high to prevent the ~.o.rch of plants in the Iudwgi
Nasturtium-I c o Fontinlis groups.

In regard to Lake Okeechobee, it should be noted that, at least on the
north and east sides, vegetation was sparse or absent in the open water
Turbidity of the water and the effect of wind probably discouraged plant

establishment. The only species found growing in fairly open water were

Vallisneria and P. illinoensis, both of which have strong rhizome systems.
The turbidity of the water probably suffices to prevent the growth of plants
in the deeper water
The east shore of Crescent Lake is shallow and iMa a very gradual slope.

Growing in the hard sand was a dense mat of almost perfectly intermingled
plants of Jas and dwarf allisnera, many of the latter in flower The
frequencyibr both plants in twenty 1-square-foot quadrats was 100% an un-
usual situation which is indicative of the density of the vegetation and its
homogeneity. A lack of information on the source and chemistry of the water

precluded attempts at environmental explanations on correlations
Lake Panasoffkee is a spring-fed lake with a soft substrate and contains
large amounts of Valisneria, P illinoensis SoatohIum, and some NS.

Lake George is also fed by springs, at least t:,o of which are saline Salt

and Silver Glen Springs. The area sampled in this lake was slightly north

of the mouth of Silver Glen Spring Runo The Vegetation consisted of ValliU

neria in flower and mall amounts of Ks which ':cro, however, well distributed

throughout the area. The water was turbid and this community extended

without noticeable change in composition from 2 to 4 feet of depth, beyond

which there was no vegetation. South of the mouth of Silver Glen Run, the

water remained cledr for a greater distance away from the run and the vege-

tation was almost entirely .aa Analyses of the water north and south of

the river mouth would be of interest.
A few other lakes were observed to be dominated by species with E.A.V. 9

and/or 10, but were not sampled quantitatively. IMost of the lakes in Florida,

however, fall into the category discussed below.

B. Ponds small lakes-1- and somelarger lakes (S tands with CI Q)O

Figure 2 shows the relative frequency curves of the species in stands of
CoI. 100 through 500, The overlapping of the curves and discrepancy of their

ranges do not permit division of these stands into discrete units.

The few chemical analyses for waters in this group show low mineral

content and may therefore by designated as oligotrophic waters. There is a

general trend from oligotrophy in the stands near 100 to eutrophy in the

higher C.I. stands, manifested partially by increase in the richness of the

substrate and partially by decrease in water clarity (resulting from plankton

growth). A direct correlation with water che istry cannot be attempted at
present because of lack of analyses for most of the stands.
There are two stands which bridge the gap between the most eutrophic

stands in this series and the least eutrophic in the springs series. These

are in Lake Reedy (Polk Co.) and have continuum indices of 581 and 680. The
first stand has high frequencies of proliferating sedge, Eleocharis elogat1
and Vallisneria. The second has proliferating sedge, Vallisneria Chara
and a little M The water of Lake Reedy, which has an area of around

5 square miles, is unstained and the substrate of these stands was sand

which made moderately soft (and probably more eutrophic) by an admixture of

organic matter. The presence of an algal bloom in the water indicated at

least a moderate degree of eutrophyo It appears that a lake of this type

so

ty rrmmrlai

TAW WM I

}
S--

I -:

\ Proltferatig sedge

Ga 44,

/

xi

/
/

/

N

\

It

/W-w o -4 AowA NIP

20 a3%wi1%0

1 /L mA A&

0S--
0 t "o W
N0o of stands 7
0. 1, 100

/

1.

II1

~00 ` ~T300
VW%^ At A%^.A
m9o
AmHaw AadroA NA b o 0174mt 10 ffftw,
lu
AcI.orieag

B \i
r
a
~
lc~L

M

4-

8 3D

1
4~a

500

/

do

.

e~y I
.,,OO

WX jaj jr I 4SWW2yL%
imaws i~PQ o Aej616 F&T#XVO I "GavFIsFeqGLN VU%;&Wla 4&" v L~s~~\a ~ sle-~a~~e

it

is intermediate between the two main groups which have been discussed, and

it shows that a combination of the species of both groups is possible* It

is likely that if there were more lakes of intermediate water quality in

Florida, the gap between the two main groups would disappear, leaving a

continuum of stands ranging from the most oligotrophic to the most eutrophic

and saline. For practical purposes, however, most of the inland waters of

Florida can be included in either the oligotrophic or the eutrophic series.

Most of the stands in the oligotrophic series are in small, unnamed

lakes or ponds, but some are in larger lakes and include those which are

listed below with their continuum indices:

Lakej in which stands occurred C.I. of stands

L. o eir, Marion Co. 100
Clinch L., Polk Co. 100
Caloosa (Crooked) L., Polk Co., 100
Dinner L., Highlands Co. 131
Swan L., Putnam Co. 194, 300
Big Thomas L., Pasco Co. 228
Lo Drooklyn, Clay Co. 243
L, Geneva, Clay Co. 386

C, orgnicdgstroph
There are certain waters which deviate from the general gradient of

oligotrophy to eutrophy because of an excess o organic matter. Extremeo

of this type in Florida are the lakes and ponds ;.ih brown-stained water

and peaty substrate Those which have vegetation are dominated by Utriou-

lania Epauriag U. frolk2s^ and =michlurn het tophyllum

Vegetation was correlated with the different degrees of organic dystrophy

in the following ways All stands in the oligotrophic series were classified

into three groups:

lo Those with clear water and sandy substrate, i.e., no dystrophy

2. Those with stained water or peaty substrate, i. e., some dystrophy

3o Those with stained water and peaty substrate such as bay head ponds,
i.e., much dystrophy,

The percentage presence of each of the common species was then calculated

for each of these three groups The results are expressed graphically in Fig.

3. It shows that there is a gradient toward organic dystrophy apart from the
gradient of oligotrophy to eutrophyo Most of these dystrophic stands fall

into the C.Io range 300 to 500, just as most of the saline stands in Florida

fall into the 900 to 1000 range. This is illustrated in Figure 4h The num-

bers and positions of the dots representing stands are purely diagramatio,

but it is hoped that further work with the available data will allow an ac-

curate scatter diagram to be drawn.
Dystrophic waters contain abundant vegetation only when they are small

and protected from wind and water movement, such as incipient bay heads.

Large brown-stained lakes, such as Newnan's Lake and Sante Fe Lake in Alachua

County have sparse submerged vegetation or none at all.
lmriophllw heterophyllm, which is one of the dominants in stands with

extreme organic dystrophy, was also present in small amounts in Ichtucknee

Springs. It occurred there in the shallow water near a shore where the sub-

strate was highly organic. Thus a tendency toward organic dystrophy in part
of a eutrophic spring may permit the occurrence of a species which does not

ordinarily occur in eutrophic water.
Notes on Taxnom andIdentification of Some Florida Submerged Plante

Ecological study often affords opportunity for observations pertaining

to the identification of species and their ecological forms. These notes
are therefore submitted both as taxonomic or identification contributions

and as explanations of the taxa discussed in this report. Specimens will

be deposited in the University of Florida Herbarium at Gainesville
A., Vallisneria

Valhisneria americana Michx, has a distribution in eastern North America

from James Bay to the Greater Antilles V, neotroicalis Marie-Victorin occurs

in Florida and Cuba, the latter being the type locality (Marie-Victorin, 1943).

The two species differ in the following characters:

8Qa

70

40

2o

20

0

Dyst rophy:

Wign e e3.

?6

i
\I

P. capillaceoas

None ome Much one some Much

Presence of species in three groups of stands, relating species to
amount of dystrophy in environment.

Dystronty (organic)
A^

S |

rtP%0p

4

0

a
S Q 0 6 @ O

vO,

ai 4 Dica showing relationt- e f dystrpho and saline stands to the
*lgotrophyeutronthy gradlant

a

9
e a
rB~~ k

0

*

T* 2jlg~~~~~lt~ t zpy raauiiijiuw^i^pR^
103~s a aga

e

0

-s .f,

--~--~--~cn-~-rr~---~*~s~-sY-*rarra~,P

L>, EmtvPvpb~

~m;u~a~-- ----76C--- --------rs~rcr IIII--= ..--.---~-~---Y~--- ~_1~L---

Increasing~e
Saliniaty

wlww0(im

so
ibii?41

Character americana VI netropicalis
leaf width 3-10 pm. 15-20 mm.
leaf opacity translucent opaque
marginal ciliation cilia small and far apart strong dentiform
if any, or just at leaf. marginal cilia
tip
pigmentation none red longitudinal bands
sepal length 2-3 mma 4-5.5 mmo
sinus of stigma lobes less than 1/2 of lobes to lower 1/3 of lobes

In its overall aspect, then, J .neolopcal is a large edition of V.

amnricana. During the present study, Vallisneria plants were encountered

which could not be differentis~aed from the typical V. americana: according to

its description (,icha-x, 1003, Gleason, 1952) and in comparison with specimens

from more northern locations, IHowever, most of the specimens collected in

Florida were intermed in in: varying degrees between V. americana and V.

neotropicalisp and some e:ven o:ceeded in their dimensions the type specimen

of Vallisneria, as described by MarieVictorin.

3I order to clarifE y ie tV;xonomnic position of the Florida Vallisnerias,

the specimens collected ,oro indexed in the following wayp according to the

methods of Edgar Anderson (19.9): The four characters which could be deter-

mined from every speciment including those with only vegetative parts, were

assigned three values according to whether they were characters of VJ americana
V. neotropicalis, or :-intermediate. The value for all four characters were

combined for each specimen to give its hybrid index.

Character O V. ericana intermediate 2 V. neor pcalis
greatest leaf width up to 10 mm. 11 to 11 mT. greater than 1 amm.
red banding weak or none medium strong
cilia/cm. (2" above base) 0,5 6-14 more than lh
size of cilia none or small medium large

The indices range from 0 (typical V. americana) to 8 (typical VS~ otropicalis).

The distribution of species according to their hybrid indices, together with the

waters in which they occurred is shown jin Table 3,

Table 3o Hybrid Indices for Florida Vallisneria specimens.

No6 of specimens

2

5

12

2

2

2

yIBrld Index

0

1

It is obvious from this that there aive more specimens with intermediate

vegetative characters than there are specimens which fit the descriptions of

either species.

These four characters and the length of the sepals were plotted, for the

Florida specimens, in an Anderson-style scatter diagram, as shown in Fig. $.

An equal number of Wisconsin specimens, selected at random from the University

of Wisconsin Herbarium were also plotted. They were all restricted to the

shaded area on the figure.

This work casts doubt upon the validity of Vallisneria netropicali a

species, Not only is there a gradient of specimens between V. americana and

.. notropicalis, but some specimens from Florida (Lo Panasoffkee) differ
more from V. americana than does the type specimen Vo neotropieals. This

makes the latter appear to be merely an intermediate form in a gredient froe

S. aeriqnan to a Valnineria like that in L. PanasoffMke or one even more
extreme which has not been collected Furthermore, it cannot be determined

Locations

Poe, Weeldwachee Spring runs

Weeld.wachee, Silver Glen, Manatee, and
Silver Spring runs, and Crescent Lake.

Poe, Silver Glen, Green Cove, Silver,
VWeekivachee Spring runs, and Crescent Lake.

Silver, Silver Glen, Green Covery Spring
runs, and Lake Harris

Silver Glen, Manatee, Silver, Weekiwachee,
Green Cover Spr. runs.

Coleman, Green Cove, Blue (Alachua Co.) Poe
Spring runs.

Rock, Poe Spring runs.

Coleman, Blue Spring runs.

Lake Panasoffkee

2

3
3

6

7
8

4;
v

t
44

"4

34
32
30
28
26
24

20
18

14
1-
10

4

2
0

3o5

3*O0

bob &

~4y

"" aa- a
Sg6
0
0 A
6 4to0 6

ao 8.s2 '

6

A 4.

Oi1Za isze
r,-y~u03

0

None
r -small

6
~idt~aaJ

Medium

Area coverI edby
Vi sconsin apecims

Oreateat lea width (in m,)

ioxrpholoical characters of Florida Yalliineri

0~~a

1 I- -- --1 U -~ ~I _- _I_-- _~ ~____---C---- L-.- I-C^- -I L --yC

from the present data if the intermediates populating Florida are hybrids

between the two extremes, or ecological variants of V americana. Further

work is in progress on this problem but in this report all specimens have

been recorded as Vallisneria sp.

B. Eleocharis eloneata

In the oligotrophic and slightly dystrophic ponds and lakes of Florida

there is an abundant sedge which was an identification problem for several

months of this study because of its occurrence, often in deep water, in a

submerged sterile form. It has a rhizome, usuaJJy red, from which clusters

of a few threadlike flexible culms, commonly 1-6 dm. long, arise at inter-

valso No proliferating form of this species was found and its variability

seems to be limited to a gradation between a cltumIp of many culms with no

apparent rhizome and clusters of a few cul3a scattered along a long rhisome.

Specimens were found in Nay and June in Lake Geneva and the Palattakaha

Creek (Lake Co.) which were connected by their rhiso-e to emergent, flowering

or fruiting culms of E elon.ta.

G. o.iferatJingsedye
This refers collectively to most of the suoB;irged sterile proliferating

plants in Florida which have been called iebsti subiersa S Hart Wright

Scirus confervoides Poir., anid Eleochari viv,,aa, Link The available

taxonomic literature on sterile submerged fon~r is not considered sufficient

for reliable identification of the specimens encountered aid collected in

this study, but the great variability among them suggests that these prolifera-

ting sedges are sterile submerged forms of at least two, and probably more,

species of Eleocharis and/or SeiPu The tendency of both genera to produce

proliferating amphibious forms lends support to this hypothesis.

D. Eleocharis Baldwinii

Another submerged sterile proliferating sedge is a form of B. Baldwinil

which grows in dense mats on the substrate of somz Florida oligotrophic lakes

and ponds. This form is finer, smaller than, and of slightly different character

than the small, fine forms of Proliferating sedge. It has been found growing

with fruiting specimens of E Baldwinii and is apparently, although not posi-

tively, the same species.

E.-Utriculia reasupista

UL resuinata, as it is commonly found, has a flowering branch which

may .be accompanied by a few inconspicuous leaves rising, near its base, from

a delicate rhizome. In many of Florida's oligotrophic lakes and ponds, however,

the small (1 1/2 to 5 eo long) linear leaves grow in such abundance that they

carpet the sandy substrates in a kind of aquatic turf. Their dark green color

against the thin layer of dark organic matter or silt which usually covers the

sand camouflages the little plants so well that the pond or lake bottom

usually appears bare of vegetation The bladders are sparse and delicate and

can easily escape detection. In the spring, the sterile form, which often

grows in deep water, was found attached to flowering plants of U~ resupnata

at the edge of the water and the identity of the submerged form was established.

The sterile submerged form is the most common plant in Florida's oligotrophic

ponds and lakes and is often the only species on the substrate,

F, Sa.ittaria ss
Another identification problem was the submerged, sterile foras of one

or more Sa ittariaspecies which occur in the oligotrophic ponds and lakes.

Identification of these was not certain enough to warrant speciatio n this

papers

The confusion occasioned by the presence of various sterile forms of

proliferating sedge, Badwinii, and the various Utricularias, which were

not clearly separated or identified until spring, resulted in the invalidation

of the data of many stands which were sampled during the winter.

G0 Chara
Chara species have been undifferentiated in this report as the species

were not distinguished during field work, This should be taken into account

when the position of Chara on the continuum is considered. It should al&o

be noted here that one or more Chara species, different from those plotted

on the continuum, has a high salinity tolerance and is found in abundance

in waters beyond the main scope of this paper, i.e., brackish coastal

waters. West Lake in Everglades National Park, for example, has a great

abundance of Char anid some JZage as well,

Literature Cited:

Anderson, Fdgar, 1949. Btro.rcssive Hybridization. John Wiley and Sons,
Inc., N, Y. and ChLpman & Hall, Ltd., London,
Bourne, d, S,, 1932. Eccloical nd phyologicagical studies on certain aquatic
angiosperms. Contre Boye Thompson Inst. 4:425-496,
Gleason, H. A, 1952 The nIfo Britton and Brown Illustrated Flora of the
Northwestern United States and Adjacent Canada, Lancaster Press,
Inc., Lancaster, Pa.
Marie-Victorins 1803, Fr, 1943. Les Vallisneries Americanes. Contr. de It
Institute Botanique de l'Universite de Montreal. No. 46, 35 pp.
Michaux, A. Flora boreali-anericana 2:220. .

4 ^ ^

STUDIES ON FISH POPUIAT:IOUS
-i d-Fo 9er9
D. K, Caldwell, H. T. Odum, T. Hellier, and Fo Berry

During the summer of 1955, studies begun over a year previously were

completed in the form of a paper (Caldwell, Odcun, Hellier, and Berry, see

list of publications and manuscripts). Scale were read. for specimens of

Stnmpknockers and bass collected over an annual cycle. The measurements

of rJins were converted into standard lengths. Growth of stumpknockers

was estimated by measuring growth of caged fi 1h in 4 enclosures for three

week periods. Gonads and gut contntts of bas stEupknockers, Gambusia and

MolJienesia were surveyed. The following s'a:riaing statements are taken

from the above cited paper

"Growth rings in stuCmpknockers are apparently too frequent to be annual

and awe not correlated with the tie of year. The sturipknocker population

reproduces mainly in spring and summer altlhc;s th ci isL evidence for some

scattered winter breeding. Age classes on length frequency diagrams are not

distinct Reproduction by bass appears to be chiefly limited to spring and

summer. *Thus even with a constant temperature> there are apparently

cycles in the life history of these fishes which cause the periods of in-

creased reproduction to coincide with periods of nmnch greater food production.

Pecaptures of tagged bass and measureemnts on stumyi.aockcrs in cages within

the springs provided some data indicating moderate growth rates (bass, .083 me/

day; sftirpknorkers, .12 mm/day). Tagging with individual color combinations

for visual study indicated little movement by stunmpknockers, but a high mr

salityo The seasonal activity of centrarchid populations are thus adjusted

to make use of maximum flow of productive energy in spring and summer and are

thus correlated with the photoperiodic cycle," This work was reported at the

American Fisheries Society meeting in Augusta, Georgia. A complete report in

the form of the published paper should be a available for the final report

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